I remember a song called Daddy's Hands:
Daddy's hands were soft and kind when I was crying
Daddy's hands were hard as steel when I'd done wrong
Daddy's hands weren't always gentle
But I've come to understand
There was always love in Daddy's hands
Was it a Christian song? No. But it was a good song.
Then again, I have heard that same song sung by... er, somebody I won't name, a popular singer, and it didn't move me at all. The singer was singing it just for show. You could hear the calculation in every note, you could tell the singer was deliberately singing it for what was supposed to be greater effect. Bleh.
The song can still be good when it's not about God, but the singer always, ALWAYS has to be able to understand what the song is about. That's why some young people can't sing certain songs well, because they haven't been through the situations the songs are talking about.